The Republican candidates for president faced off in their second debate of the weekend this morning in New Hampshire. Last night, front-runner Mitt Romney was able to stay above the fray, as his opponents attacked each other in the fight for second place. But this morning, they turned their fire on Romney.

(SOUNDBITE OF POLITICAL DEBATE)

RICK SANTORUM: At the end of that campaign, he wouldn't stand up for conservative principles, he ran from Ronald Reagan and he said....

REPRESENTATIVE RON PAUL: I don't see how we can do well against Obama if we have any candidate that, you know, endorsed single-payer systems and TARP bailouts and don't challenge the Federal Reserve's 415 trillions of injection, bailing out their friends....

MARTIN: With the debate now over, Rick Santorum and Rick Perry will skip ahead to campaign in South Carolina later today. But NPR's intrepid national political correspondent Mara Liasson is still in Concord, New Hampshire, and she joins us now. OK, Mara, how did the former Massachusetts governor handle all these attacks?

MARA LIASSON, BYLINE: Well, I think he handles them fine. I mean, there was no deer-in-the-headlights moments, no brain freezes or angry outbursts. I think that Mitt Romney, like he is prepared for everything, he was prepared for these attacks. And as a matter of fact, his campaign thought that they would be coming sooner. But they finally did come this morning and I think it is significant that they finally did. You heard Newt Gingrich needling him. He went on to say that Romney was full of pious baloney for suggesting that he selflessly didn't run for reelection in Massachusetts, as opposed to being on the verge of losing. And Ron Paul and Rick Santorum also attacked Romney for not being sufficiently conservative or consistent.

MARTIN: But Santorum kind of seemed torn between going after Romney and his closer rival, Ron Paul. How did he work this out?

LIASSON: Well, he did both. He went after Romney for not being a Ronald Reagan conservative. He also went after Ron Paul. He said that all the things that Republicans like about Ron Paul; he can't possibly get accomplished because he can't work with other lawmakers in Washington. Ron Paul has introduced over 400 bills and I think maybe one of them has become law. And he said the things that you don't like about Ron Paul - the foreign policy positions, he can accomplish on his first day as commander in chief.

MARTIN: But Ron Paul was on the offensive, too. Who was his target today?

LIASSON: Well, he's targeting everybody. Ron Paul went after Rick Santorum for being a big government conservative. Ron Paul went after Mitt Romney for being in favor of a lot of things Republicans and conservatives don't like. So, Ron Paul exists in a universe almost unto himself. He has a Libertarian base that wouldn't even necessarily vote Republican if he wasn't the nominee.

MARTIN: So the attacks are now coming fast and furious against the front-runner, former Massachusetts governor Mitt Romney. But really, Mara, has anything changed? Did anything happen this morning that has fundamentally changed the dynamic of this race?

LIASSON: I don't think that there was a game-changing moment this morning. I think Republicans were reminded for the first time in a concerted way of all of the doubts they have about Romney, why they haven't warmed up to him. Now, of course, in New Hampshire that's not as big a problem for him because he's running so far ahead. The latest Suffolk University poll has Romney at about 35 percent. That's a little bit less than the 40 or 43 percent he's been polling previously. So, he's coming down a bit. Ron Paul is a solid second place with 20 percent, and you have Huntsman, Gingrich and Santorum all battling for third place. Huntsman is at 11 in this poll, Gingrich is at 9, Santorum is at 8.

So, now they have to battle each other if they're going to have a third place finish. Right now, Ron Paul is Mitt Romney's friend. Anything that keeps the more legitimate, viable candidates suppressed in New Hampshire, denies them the boost they need to go into South Carolina and Florida is a good thing for Mitt Romney. I think Romney would have to end up probably under 30 percent to have a super disappointing finish here in New Hampshire. But right now he seems very well set up to come out of New Hampshire with a boost, go on to South Carolina and Florida, where he has a lot of money for ads and where he is polling ahead in both those states.

MARTIN: OK, we'll see how things play out on Tuesday in the primary. Thanks, Mara.